The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft is driven by one or more propulsion unit(s), each comprising a turbojet engine housed in a nacelle.
The modern nacelles are intended to accommodate a bypass turbojet engine, adapted to generate a hot gas flow (also called primary flow), coming from the combustion chamber of the turbojet engine, and a cold air flow (also called secondary flow), generated by the blades of the fan of the turbojet engine and circulating outside the turbojet engine through an annular passage (also called flow path) formed between a fairing of the turbojet engine (or an inner structure of the nacelle surrounding the turbojet engine) and an inner wall of the nacelle. The primary and secondary flows are ejected from the turbojet engine from the rear of the nacelle.
A nacelle has a tubular structure usually comprising an air inlet in front of the turbojet engine, a middle section intended to surround the fan of the turbojet engine, and a rear section, the rear section generally accommodating thrust reversal means and being intended to surround the combustion chamber of the turbojet engine. Furthermore, the nacelle is generally terminated by an ejection nozzle whose outlet is located downstream of the turbojet engine.
The rear section of the nacelle is usually formed of a first and a second half-shells of a substantially semi-cylindrical shape, disposed on either side of a longitudinal vertical symmetry plane of the nacelle. The middle and rear sections are, conventionally, connected to one another by a frame, the first and second half-shells being generally equipped with positioning means cooperating in the working position with complementary positioning means formed on the frame.
Given the size, weight and relative fragility of the members constituting a nacelle, the finishing, final assembly and handling operations are complex, time consuming and involve expensive equipment.
The finishing operations comprise, in particular, the painting operations, which are important for the final quality of the external appearance. However, these operations do not seem to be currently optimized in terms of quality and speed of execution.
Conventionally, the painting operations of a nacelle are performed by means of support carriages dedicated to the different subassemblies of a nacelle, namely the air inlet, the two half-portions forming the middle section and the two half-portions forming the rear section. Each of these members is thus fastened on a corresponding support carriage to be painted by an operator. Examples of these known devices are represented in FIGS. 1 and 2. FIG. 1 shows a painting tooling 100 for a nacelle air inlet 101. FIG. 2 shows a painting tooling 200 for a nacelle rear half-section 201.
This conventional method has several drawbacks. Firstly, it involves a significant number of specific equipment, including not less than five different support carriages for a single nacelle. Furthermore, for the most voluminous members, the operators are forced, in order to access all the areas to be painted, to use platforms of different heights, thereby implying for the operators a highly degraded ergonomics.
Different operations subsequent to the painting operations are also impacted by bad ergonomics and efficiency.
Indeed, once the painting operations are completed, the nacelle is equipped and mounted on a motor, said “slave motor”, in order to perform the last quality control (including, in particular, a dimensional control). Therefore, this implies having to handle each of the subassemblies of the nacelle in order to mount them on the slave motor, with the risks and the difficulties it includes. Then the nacelle is presented to the customer mounted on the slave motor, so that the customer may perform the controls and decide whether to accept or not the delivery of this nacelle. Finally, the nacelle is detached and the subassemblies are installed on specific transport carriages to be delivered to the customer. Handling operations are therefore performed on several occasions.
At each step of this process, the handling of the members constituting the nacelle is an important operation because the nacelles are very heavy parts and of very large dimensions, but relatively fragile. Generally, the precautions for the handling of the nacelle members are time-consuming.